单选题Which test checks the transmitter and receiver of a local modem？（）A data parityB analog loop backC local digital loop backD remote digital loop back

A. It checks the database for intrablock corruptions only.

B. It checks for block corruption in the valid backups of the database.

C. It checks the database for both intrablock and interblock corruptions.

D. It checks for only those corrupted blocks that are associated with data files.

A local-area network(LAN)is a communications network that(125)a variety of devices and provides a(126)for information exchange among those devices. The scope of the LAN is small typically a single building or a cluster(丛)of buildings. The LAN is usually owned by the same organization that owns the(127)devices. The internal data rate of LAN is at least several Mb/s.The basic of LAN communication is broadcasting. At each station, there is a transmitter/receiver that communicates over a(128)shared, By other stations. A transmission from any one station is(129)to and received by all other stations.

A．broadcast

B．cable

C．control

D．interconnects

E．internet

The person sending a message is NOT influenced by which of the following

A sender's credibility

B receiver's assumptions

C receiver's evaluative and tendency

D receiver's attitude and needs

E sender's knowledge

______ is not a factor which will affect the accuracy of GPS receiver．

A.detective Availability

B.local environmental conditions

C.autonomous mode versus differential correction mode versus RTCM mode

D.the averaging of recorded locations

A. fiber dispersion

B. signal attenuation

C. transmitter power

D. amplifier bandwidth

E. receiver dispersion tolerance

A.It prompts you to set the root user account password

B.It checks whether file permissions are appropriate within datadir

C.It asks to remove the test database, which is generated at installation time

D.It can delete any anonymous accounts

E.It verifies that all users are configuration with the longer password hash

A. tracert

B. msconfig

C. route

D. net use

195 The person sending a message is NOT influenced by which of the following

A. sender's credibility

B. receiver's assumptions

C. receiver's evaluative and tendency

D. receiver's attitude and needs

E. sender's knowledge

Click the Exhibit button. Given the following parameters: transmitter output (min): -2 dBm receiver input (min): -28 dBm 15216 Mux and Demux loss: 4.5 dB 16 channels maximum In which sites shown in the exhibit could the 15216 EDFAs be placed to minimize the number of EDFAs needed?（）

A. Locations B, C only

B. Locations A, B, C only

C. Locations A, B, D only

D. Locations B, C, D only

E. Locations A, B, C, D